The old postal slogan about mail deliveries despite rain, sleet and snow needs amending.

It should now include "except on days we can't afford to deliver the mail."

The postmaster general asked Congress last month to lift the requirement that the agency deliver the mail six days a week.

Dropping mail volume and increasing costs left the agency $2.8 billion in the red last year. And the prospects for this year aren't any better.

Postmaster General John E. Potter pointed to two problems in an Associated Press story.

"A revolution in the way people communicate has structurally changed the way America uses the mail," with a shift from first-class letters to the Internet for personal communications, billings, payments, statements and business correspondence, he said.

To some extent that was made up for by growth in standard mail - largely advertising - but the economic meltdown also resulted in a decline there, Potter noted.

We would suggest there is a third problem.

The postal service continues to try to fix the situation by raising rates. In was announced Tuesday that postage stamps will increase 2 cents in May.

Higher prices provide another incentive for Americans to switch to online services. Also, there are other competitive parcel delivery services to cut into the agency's bulk mail deliveries.

Delivering the mail just five days a week will give Americans another opportunity to find other ways to communicate, driving them even farther away from the postal service.

Reducing mail delivery to five days a week, likely dropping Tuesday, will save money.

One study estimates it will save the agency $1.9 billion annually. The postal service thinks it will save $3.5 billion annually.

The question is whether the savings will translate into the long-term viability of the agency.

Or does the postal service need to look at phasing itself out as the major mail delivery system in the nation? It could retain responsibility for delivery of official government correspondence and turn the rest over to private enterprise.

At the moment, it doesn't appear the postal service will make a quick change to five-day delivery. But it can't be slow about change. It needs to find a way to eliminate the losses and become a cost-effective service.

Otherwise, the weather won't stop deliveries. The inability to weather the economic times will be the agency's downfall.